There have been a handful of times when I am sitting alone, crying, staring off into space, paralyzed by the sadness and anxiety...I have been able (with much effort) to stand up, and go outside and walk around.
It's no "exercise" (which I TOTALLY understand not having time for) but it does benefit your body and your feelings. Even for 10 minutes, just getting a little air, the blood flowing a little...
Maybe give it a try? Even at work on a lunch break or something, take a walk around the building or parking lot if it's a safe area.
I hope that whoever is using you for a verbal punching bag can come to realize how much they are hurting you and stop.